1. Field of the Invention
The present invention relates to a technique for generating an image representing a normal structure of a predetermined structure within a subject contained in an input medical image, and a technique for separating an abnormal component in the medical image.
2. Description of the Related Art
As a technique for separating an abnormal component in a medical image, a computer-aided imaging diagnosis system (CAD: Computer Aided Diagnosis) has been known. The system automatically detects a candidate abnormal shadow in the image and displays the detected candidate abnormal shadow in an enhanced manner.
For example, a technique has been known, in which a first shape-dependent filter, such as a morphological filter, is used depending on the shape of a small calcification shadow to generate a small structure image, and then a second shape-dependent filter which meets imaging conditions, and the like, of the small structure image is used to generate an enhanced image (see, for example, U.S. Pat. No. 7,242,794).
Further, a technique has been known, in which a model representing a shape and texture of a normal structure of a subject, which is obtained by a technique known as AAM (Active Appearance Models) is applied to an inputted image to generate a normal structure image, and then differences between the inputted image and the normal structure image are calculated to detect an abnormal shadow (see, for example, Japanese Unexamined Patent Publication No. 2004-041694).
However, since abnormal tissues with calcification may take various shapes, there still is a room for improvement in accuracy of recognition, even if the above image recognition technique described in U.S. Pat. No. 7,242,794 is used.
The use of the technique for separating an abnormal component based on differences between the inputted image and the normal structure image described in Japanese Unexamined Patent Publication No. 2004-041694 allows separation of the abnormal component without depending on the shape of the abnormal tissue, however, there still is a room for improvement in accuracy of the generated normal structure image.